Went to the autoparts store today to buy a K&N cone filter for my short ram air intake I recently purchased off of eBay. I realized that the K&N filters don't have adapter moldings to connect to the MAF/throttle body. A guy behind me overheard my convo and so it began...

Tim: What kind of car do you have?
Me: Nissan Maxima
Tim: Hmm, yo man, I'd be careful with aftermarket intakes
Me: Really? How come?
Time: Well, a lot of times, engines run lean after installing intake. Did you reset the ECU? Any CEL?
Me: Yeah, I reset it. No lights. No prob.
Tim: I dunno man. Anytime you install intake, your bringing in more air into the engine. It could really screw up your oxygen sensors and ****.
Me: What do you recommend I do?
Tim: Take it a performance shop. They can run a bunch of tests on it and see whether your air-fuel mixture is correct. I think the norm is 16:1 or something like that.
Me: So you're saying that after I install my aftermarket products, have them reprogram my computer cuz a lot of times the ECU can't fully adjust?
Tim: exactly!


So....What do you guys think??

hes retarded dont talk to him about moding ur car anymore

lol dont listen to him...

can someone explain why just don't say hes retarded explain him why

HAHAHAHA please tell him to go fawk himself. haha, first off... since we have Electronic computeres these days... cars tend to figure out what is going on in almost every aspect of the car. For instance, with an intake, you add it and more air flow is the consequence. The ECU says "hmmm, more air... we need more fuel then". Whaa laaa... problem fixed.

Yup. That's the whole point of the mod. Sorta.

I have been running aftermerket intakes for years, he is a dumb ***!. The computer will adjust to the A/F there is not THAT much more air than normal.

does your Maxima Club of California have a website? i should probably type it in, and look first

No hes right... Youll also have to upgrade your ECU to Direct X 9

I dont know, my mechanic said the same thing....

read this

http://forums.maxima.org/showthread.php?t=321733

I will never trust those auto parts store guys again... I let them install an airfilter once because I didnt have the screws to open the airbox.. turns out the bastard breaks my maf adapter as well as a part of my airbox, and then he tried to hide it...

This ones better
http://forums.maxima.org/showthread....77#post3056077

ok, lets clear up a misconception here. when you install an intake or a better filter, you ARE NOT adding more air to your engine. period. There is a given amount of space in your intake tract and at normal atmospheric pressure, that volume of air is the same, reguardless of your intake setup. The thing that you ARE doing, is allowing the air to flow more freely through the intake, which in turn allows the engine to breathe easier. This slightly increases how fast the engine can take in air, but dont be fooled, there is no more air than normal in the combustion chamber. To put more air in your combustion chamber, you would have to compress the air in your intake tract. (supercharger, turbocharger, NO2) so in reguards to the moron working at the auto parts store, dont listen. He will be slinging spark plugs for a long time.
Hope this clears some things up.

I think my intake did nothing but good

The ECU is uses predetermined AF ratios and the only way to adjust those are by reprograming it.

umm, so you're saying that the guy WAS right? How necessary is it for my car's integrity that I get the ECU reprogramed?

Of course the ratio is predetermined, that doesn't mean that it cannot adjust the amount of fuel based on the ratio.

dude i think its a bunch of BS! Ive installed a million intakes and every car ive ever had, had em. never a problem.

lol that's funny. ask that guy what kind of car he drives. i bet it's a 73 camaro with t-tops and bondo or something similar. was he wearing a wife-beater and sporting a mullet? next time he tries to talk to you, first welcome him to 2004, then tell him to go tune his carburetor and leave you alone!

No, I am saying that your ECU will, to a point, be able to maintain it's predetermined AF ratio when you add mods.

And there is only two companies in the country that I know of that know how to reprogram our ECU's....so it's not like you can just take it to some random speed shop.

Yes, and......?

HAHA. One would think so, right? Actually... the guy owned a Ford (Found On Roadside Dead) F350 turbo diesel. He worked as a sales manager at a local car dealership and landscapes as a 2nd job. So, your redneck portrayal is SOMEWHAT accurate.

ok. So you're saying that when you do aftermarket mods, you're kinda screwed if you ever want to get optimal performance (that being the proper AF mixture)?

What about buying an AF A-pillar gauge? Would that allow one to accurately see whether the ECU is properly adjusting to the increased air flow velocity?

If you want your AF ratio adjusted then you must either get your ECU reprogramed by JWT or TC or get an SAFC.

Dont' worry about this AF ratio thing. Untill you add some major HP mods you don't really need to worry about it. The ECU will take care of things

16:1 is REALLY LEAN..your engine would be shot at 16:1...I would have turned around right there and walked out on the conversation...Our Cars run at 11.5:1 ---12:1...even 13:1 is lean....the kid had no idea what he is talking about

-matt

I think people are getting a little confused here. Ratio = amount of gas/air flow or air flow/amount of gas. Bring in more air, the amount of gas will have to go up to maintain the same ratio.

Man I'm jealous!!!! You got one of them Electronic computers!!!

My ol cow uses an Abacus!

Like the Keyser said, I have never had any problems either. I also have been using them for years. The other thing is that my brother is my mechanic. He is fanatical about cars. He would never have let me do that to a car as nice as the maxima if he thought it would cause problems.

.

On a N/A car I think 13:1:1 is fine. I think they say the perfect ari fuel ratio is 14:1:1 but it really does not work in every day driving. On a boosted car you probally want to stay around 12:5:1 or lower.

the MAF will sense how much air is going in, then telling the ECU to put the right amount of air.. unless your ECU is as retarded as that guy...that is a different story. It isn't blown so don't worry about.

The moron at the parts shop is an idiot......

Well there is some truth to what he was saying. I've heard of civics and stuff leaning out with full bolt-ons. Don't know why that happens, but it might be because they have an MAP that estimates airflow as opposed to our MAF that actually meaures it. Bah who knows...

Some people know nothing about maximas....or cars in general at that.

if he starts talking about flux capacitors, then get the hell out of there.

Hey, the guy at my local Kragen just sold me a new flux capacitor, now the car runs real gooood. Seriously though FYI the stoichiometric ratio for normal (without oxygenates) gasoline is 14.7:1. The addition of ethanol, MTBE or other oxygenates will lower that number slightly...

I wouldn't be so fast to assume the guy was retarded, as some of you said in the first two replies.
I was watching Sports Car Revolution the other day and Shawn Hyland said something very similar to what "Tim" told MaxxAddict. I'd take Hyland's opinion over any of you guys' any day.
I am no mechanic, but Hyland's explanation made perfect sense and to the tee described how my car acted with the intake on.

Tell Him To Sell His 1979 Honda Civic Si-r Type R 0.5L I-VTEC

there is truth to what he was saying, there are limitations to every fuel system i.e. inj., fuel pressure regulators,etc. now if you have a lot of bolt ons it can cause you to lean out because your fuel system cannot keep up and you will have problems. most people don't believe these mods can cause this due to the fact " they've put intake, headers, and exhaust on all thier cars" and never had problems, of course these will lean out the a/f ratio but not enough to do any harm, but because all cars are not EXACTLY the same, some cars do have problems. besides how do they really know......if my car's a/f varied slightly i wouldn't be able to tell, and i couldn't tell you the "feel"of one a/f ratio to another. there seems to be some misunderstanding of information....


bfox55
i also believe that you can do things that allow more air into your motor exhaust, intake, and headers affect scavenging and other things that help motors to "breathe". yes the comb. chamber has a specific volume, but that doesn't mean that the motor necessarily fills that volume.

Yea some cars fuel systems cannot keep up with bolt-ons. The civic is an example. We're just fortunate that the maxima's fuel system can handle most N/A mods. Although i think Iron Lung had an issue with running lean with his cams and headers.

And as for bfox55, there will always be some sort of negative pressure in the intake manifold. The filter is what causes the pressure drop. Like fsr20det already said, theoretically atmosperic pressure should fill the cylinder completely but it doesn't some of the time.If an engine got all the air it needed at every RPM the torque curve would never drop off. A filter that flows better will cause less of a pressure drop effectively allowing better cylinder filling, but by a trivial amount maybe.